Knife sharpener



May 13, 1958 E. R. TENGBERG KNIFE SHARPENER Filed June 6, 1957 FIG. 6

. INVENTOR. EVERT R. TENGBERG BY 0%, WmfiSmZaw FIG.5

ATTORNEYS United States Patent KNIFE SHARPENER Evert R. Tengberg, Peabody, Mass., assignor to New England Carbide Tool Company, Inc., Medford, Mass, a corporation of Massachusetts Application June 6, 1957, Serial No. 663,984

6 Claims. (CI. 7688) of a household type knife sharpener of the above general description involves preferably a molded plastic one piece base and case for supporting the sharpener elements, so constructed that the carbon steel or other desirable type of hardened sharpener elements may be conveniently mounted on sharpener support elements and the support elements inserted securely in the case and rigidly retained therein.

Since the sharpener elements are expensive, they must be made as small as possible for the sake of economy, that is, only large enough to provide the necessary sharpening edges, and so they are rigidly mounted as by brazing or soldering on support elements of cheaper metal.

Various methods of placing the sharpener elements and their support elements in the casings have been worked out. While these have been for the most part functionally successful, the inter-relation of the parts and the method of assembly has been deemed too expensive and complicated.

Accordingly, it is the object of the present invention to improve the construction and assembly of knife sharpeners by simplifying the construction and inter-relation of the parts and minimizing their number so that they can be put together more cheaply and quickly and at the same time to provide increased rigidity of the sharpening elements in relation to each other and the base so as to result in a sharpener which, while less expensive, has improved rigidity and durability for resisting the stresses and abuse of long continued use.

Other objects will be understood from the description taken in connection with the drawings in which:

Fig. 1 is a side elevation of the improved sharpener in use showing the general relationship of its parts.

Fig. 2 is a partial perspective and section taken on the lines 22 of Fig. 1.

Fig. 3 is a partial enlarged bottom plan view.

Fig. 4 is a bottom plan view.

Fig. 5 is a view of one of the sharpener elements mounted on its support, viewed as on the lines 22 of Fig. 1.

Fig. 6 is a section taken on the lines 6-6 of Fig. 5.

A plastic case 5 molded in one piece has a base portion 6 and a dome shaped body portion 7. As best seen in Figs. 2 and 3, the body portion 7 has a pair of offset parallel slots 10 and 11 extending at least part way up from the bottom of the case 5.

The slots 10 and 11 are defined by parallel side walls 12 and 13 and end walls 14 and 15 and a plurality of vertical ribs and 21. One half of the total number of ribs, that is, the ribs 29 extend partially across from the side wall 12 toward the other wall' 13 and the other half of the ribs, that is, the ribs 21 extend partially across from the other side wall 13 toward the side wall 12. The

ribs 20 define a surface 22 and the ribs 21 define a surface 23. The surfaces 22 and 23 are ofiset and oppositely facing with respect to each other between the side walls 12 and 13.

The slot 10 is therefore defined on one side by the inner surface of the side wall 13, on the opposite side by the co-planar surfaces 22 of the ribs 20, on one edge by the inner surface of the end wall 13, and on the other edge by the inner surface 26 of the inner rib 21. The other slot 11 is defined on one side by the side wall 12, on the other side by the co-planar surfaces 23 of the ribs 21, on one edge by the inner surface of the end wall 15 and on the other edge by the inner surface 27 of the inner rib 20.

The slots 10 and 11 overlap to form a central space 30 which extends across between the side walls 12 and 13, and upwardly in the body portion 7.

The case 5 has a vertical knife receiving aperture 32 in the top of its body portion 7, preferably generally V- shape in form, which is transverse to the slots 10 and 11 and which extends downwardly from the top of the case into the central space 30. A pair of sharpener element supports 35 and 36 having side and edge surfaces corresponding with the wall surfaces of the slots. For instance, as seen in Figs. 2, 5 and 6 the support element 36 has edge surfaces 38 and 39 and side Wall surfaces 4ti and 41 corresponding with the end wall surfaces 27 and 15 and the side wall surfaces 12 and 23 of the slot 11.

The edge surface 38 is provided by an ear 37 on the support element 36. The support 35 has a corresponding ear 33 providing an edge surface 34 corresponding to the wall surface 26 of the inner rib 21. The cars 33 and 37 of the respective supports 35 and 36 overlap in the center space 36 provided by the overlapping slots 10 and 11.

The support elements 35 and 36 have adjacent cutaway inner edge portions 43 and 44 in V-shape relation mounted on which are a pair of sharpener elements 45 and 46 which overlap each other also in V-shape relation in the aperture 32 forming a throat 48 through which a knife 50 may be drawn in the direction of the arrow as seen in Fig. 5 to sharpen its lower edge 51.

The walls 12 and 13 and consequently the slots 10 and 11 are preferably inclined away from the vertical in the direction away from the side of the sharpener elements in which their respective shearing edges are located, that is, inclined in the direction toward which the knife is drawn, as seen in Fig. 1.

As seen in Fig. 6 with respect to the sharpening element 46, the shearing edge is formed by grinding a face 56 at a reverse angle a forming a negative rake from the face 57 of preferably 15 degrees, and by grinding a face 58 at an angle b from a plane normal to the face 46 to provide preferably a 5 degree clearance for the knife 50 behind the shearing edge 55. The sharpening element 45 is ground in the same corresponding manner.

The sharpener element supports 35 and 36 are press fitted into the slots 10 and 11 so that they are in partially overlapping relation, that is to say, so that their ears 33 and 37 overlap, and with the sharpener elements 45 and 46 in the overlapping relation seen in Fig. 2.

The side walls 12 and 13 and the ribs 24 and 21 provide a structure which is sufficiently resilient to receive the supports 35 and 36 when they are pressed into the slots and sufiiciently rigid to hold these supports and their sharpening elements securely in place.

Manufacture is therefore simple and inexpensive, there being but five pieces in all to put together, namely, the case which is formed in one piece, the two sharpener element supports 35 and 36 and the two sharpener elements 45 and 46 which are first mounted as by soldering or brazing .on the supports35and. 36. The supports 35 and 36 are then simply shoved into the slots 10 and 11 under pressure and assembly is complete.

I claim:

1., A knife sharpener of the type having sharpening elementsina generally V-shape relation comprising, in combination, a case having offset parallel slotsextending part wayaupsfrom the bottom, said slots being defined by parallel. side and end walls and including oiiset co-planar surfaces, said slots overlapping to form an enlarged cen tral space, said case having a vertical knife receiving aperture transverseto said slots and extending downwardly from its topinto said central space, a pair of sharpener element supportshaving surfaces corresponding with the wall surfaces of the slots and press fitted into partially overlappingerelation in said slots, said supports having adjacent cut-away inward edge portions in V.-shape relation, anda pair of sharpener elements mounted on said edge portions partially overlapping each other in said V- shape relation in said aperture.

2. In the knifesharpener as set forth in claim 1, said slotsv beingsinclined away from the vertical in the direction away from the side of the sharpener elements in which their respective shearing edges are located.

3. In, the knife sharpener as set forth in claim 1, said slots being formed by a pair of parallel walls spaced at twice the thickness of said supports and a series of vertical :ribs extending half way across between and from opposite interior faces of said walls in offset relation on opposite sides of said enlarged central space.

4. A knife sharpener of the type having sharpeningelements in a generally V-shape relation comprising, in combination, a case having offset parallel slots extending part way up from the bottom, said, slots being defined by pairs of parallel side and end walls and vertical ribs extending from said side walls, said ribs defining offset oppositely facing co-planar surfaces between the side walls, said slots overlapping to. form. at. central. space extending across between said side walls, said case having a vertical knife receiving aperture transverse to said slots and extending downwardly from its top into said central space, a pair of sharpener element supports having surfaces corresponding with the wall surfaces of the slots and press fitted into partially overlapping relation in said slots, said supports having-adjacent cut-away inward edge portions in V-shape relation, anda pair of sharpener elements mounted on said edge portions .partially overlapping each other in said V-shape .relation.'.in said aperture.

5. A knife sharpener as set forth in claim-4 in which the case is molded as a unit formed of. plastic material.

6. A knife sharpener of the type having sharpening elements in a generally V-shape relation comprising, in combination, a case having offset parallel slots extending part way up-tfrom-the .bottorn, saidslots being defined by pairs of parallel-side and. end walls and a plurality of vertical ribs, onethalf ofwhich extend partially across from one of the sidewalls and the other halfofwhich extend partially .across from theiother sidewall, said ribs defining offset oppositely facingVco-planarsurfaces between the side walls, said slots overlappingv to form a central space extending across between, said sidewalls, said case having a vertical knife receiving aperture transverse .to said slotsandzextending downwardly from its top into said central space, a paircf sharpener element sup ports having surfaces corresponding with the wall surfaces of the slots and press fitted into partially overlapping relation in. said slots,rsaidss upports having adjacent cut-away inner edge .portionsin V-shape relation, and a pair of sharpener elements mounted onv said edge portions partially overlapping each-other in said. V1shape relation in said aperture.

No references cited. 

